package Server;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.nio.charset.StandardCharsets;

/**
 * Created with IntelliJ IDEA.
 * User:xieChao
 * Date:2022/11/9 19:59
 */
public class UdpEchoServer {
    private DatagramSocket socket = null;
    //绑定端口号， port 就是端口号
    public UdpEchoServer(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }
    public void start() throws IOException {
        System.out.println("启动服务器！");
        while (true){
            //1.读取客户端请求
            DatagramPacket requestPacket = new DatagramPacket(new byte[1024],1024);
            socket.receive(requestPacket);
            String request = new String(requestPacket.getData(),0,
                    requestPacket.getLength(),"UTF-8");
            //2.根据需求，计算响应
            String response = process(request);
            //3.把响应写回客户端
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),response.getBytes().length,
                    requestPacket.getSocketAddress());
            socket.send(responsePacket);
            System.out.printf("[%s:%d] req: %s,resp: %s\n",
                    requestPacket.getAddress().toString(),requestPacket.getPort(),request,response);

        }
    }

    public String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoServer server = new UdpEchoServer(9090);
        server.start();
    }
}
